tree 309907b14c7ecc136f26621d2bda8e4b467889d6
parent 49a962c075dfa41c78e34784772329bc8784d217
author Steven Rostedt (VMware) <rostedt@goodmis.org> 1606796163 -0500
committer Steven Rostedt (VMware) <rostedt@goodmis.org> 1606796511 -0500

ring-buffer: Always check to put back before stamp when crossing pages

The current ring buffer logic checks to see if the updating of the event
buffer was interrupted, and if it is, it will try to fix up the before stamp
with the write stamp to make them equal again. This logic is flawed, because
if it is not interrupted, the two are guaranteed to be different, as the
current event just updated the before stamp before allocation. This
guarantees that the next event (this one or another interrupting one) will
think it interrupted the time updates of a previous event and inject an
absolute time stamp to compensate.

The correct logic is to always update the timestamps when traversing to a
new sub buffer.

Cc: stable@vger.kernel.org
Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>